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help cant get os46sf to run

Old 12-13-2001, 03:32 AM
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countryboy3
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Default help cant get os46sf to run

the motor will start but when you try to give it throttle it acts like it is running out of fuel. Rebuilt engine and carb. Please help wanting to put it on a sig kougar i just built. THANKS
Old 12-13-2001, 03:59 AM
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Taildrager-inactive
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Default getting her started

Sounds lean with the idle mixture, try 1/8 of a turn richer, make sure high speed is out at least 2 1/2 turns. Sure hope this does it . Is your glow plug working correctly
Old 12-13-2001, 08:59 PM
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Default help cant get os46sf to run

Please explain in detail your rebuilding proceedure, parts used in the process, etc.
Perhaps you have reassembled something incorrectly. Is this the ringed or ABC version of the 46SF?
Old 12-13-2001, 10:26 PM
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countryboy3
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Default os46sf

It is a abc engine, i bought a kit from os. It consists of a head shim. head gasket, backplate gasket, carb mounting o-ring, and a needlevalve. Not sure if i got the low idle mixture and spray bar right. Could this be possible. How would i know. thanks for helping. This sig kougar sure looks good, if i could just get some power to it.
Old 12-14-2001, 08:02 PM
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Default help cant get os46sf to run

The parts you purchased are hardly rebuild parts. Rebuild parts would be a new piston/sleeve combo or new bearings or a new crankshaft (i.e. moving parts that wear).

That engine came new with only a head gasket and no shim. I am a bit puzzled about your mention of a head shim as these are not normally needed on OS engines here in the states so if you have installed the shim in addition to the head gasket then take the shim out and try to run the engine. If it still hesistates and dies when accelerating then start leaning out the low end needle an 1/8th turn at at time until you get the proper instantaneous throttle transition that these engines normally provide.

Are you the original owner or have you bought this engine used? Why did you feel the need to replace the parts mentioned? Has the carb ever been disassembled?
Old 12-14-2001, 11:55 PM
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countryboy3
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Default os46sf

I bought this motor used but ran it on a gp. corsair for about four or five flights. then sold plane. Haven't been able to get motor to run since. I have taken the carb apart and cleaned it. now that you mentioned it i dont think i used the shim. How would you go about retuning the carb if i got this wrong. thanks for trying to help.....
Old 12-15-2001, 12:40 AM
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Default Your OS 46SF......

I'm wondering if this engine is like the .61SF, the carb specifically, in make up, not size.
If it is, there is a cam that goes on the side of the carb, that adjusts the mixture(slight adjustment at best), anyway, the cam actually moves the spraybar within the throat of carb to attain optimum air/fuel flow.
That cam will only work correctly when installed ONE WAY. However, there are 4 ways it can be installed(if I'm thinking correctly here). I know the 61SF has the cam and that's how it works, and a person can go nuts trying to figure out why it won't work(don't ask how I know).
You said you rebuilt carb, that's what keyed me to this, and the symptoms you describe are exactly how it would react if it is a cam situation.
If there is a cam on that carb, make doubly sure it's letting the spray-bar aim into the throat of carb, yes if it's there, there is a way it will work, if there's no cam, follow all other advice you see here in this thread. Good Luck Dale

PS If carb is similar to what I mentioned, there will only be about 1/4 of a turn total adjustment for the mixture, that's about what the .61 has, and once you get the hang of these carbs, they are not bad at all.
Old 12-15-2001, 02:07 AM
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Default os46sf

facing the motor there is a little screw deep inside the throttlecontrol arm. could this be what your talking about.
Old 12-15-2001, 08:04 AM
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Default help cant get os46sf to run

The 46SF and the 61SF have completely different carb designs so unfortunately the excellent advice above will not be applicable. Hopefully you have put your carb back together again correctly with the spray bar properly oriented. The screw in the center of the throttle arm is where you adjust the low end which I suspect is out of whack and causing your engine to die when the throttle is advanced. It could either be too lean but more likely too rich so start turning that screw inwards 1/8th turn at a time and run your engine to see how it affects the throttle transition. If your adjustmnent is now way out of whack then close the barrel of the carb and screw the low end in all the way (be gentle) and then back it out one full turn ( this will be approx the original factory setting) then and then start the engine and go thru the 1/8th turn rountine described above until you get the normal throttle response you've come to expect from an OS.
Old 12-15-2001, 08:32 AM
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Default help cant get os46sf to run

Shemp, thanks for clearing that up, I really wasn't sure the type of carb the 46 was equipped. However if you ever work on the 61sf you'll definately not forget that one. I'm sure Shemp knows what I'm talking about there.
countryboy, good luck with your engine, Shemp has you dialed in on this one. If prob persists though, expand the search to and include fuel lines/tank. You did say you haven't had motor to run correctly since last plane, right? . Just thoughts here guys. Regards, Dale

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